Self-locking nail



Feb. 8, 1966 HANDJA 3,233,498

SELF-LOCKING NAIL Filed April 8, 1963 NVENTOR HA NDJA United States Patent C) 3,233,498 SELF-LOCKING NAIL Joseph A. Handja, 3316 W. 6th Ave., Vancouver 8, British Columbia, Canada Filed Apr. 8, 1963, Ser. No. 271,274 1 Claim. (Cl. 85-20) This invention relates to improvements in self locking nails and partcularly to a fastening device of this nature which is intended for use in material having poor or diminishing nail holding properties.

The use of only partly seasoned lumber and of composition boards such as asbestos cement and the like is becoming more and more common in the building trade and this has presented a fastening or nailing problem which is causing concern. When a conventional nail is driven into such material the load it will support is reduced to a large extent and will often decrease still further as aging takes place. This means either a greater number of nails must be used for a given area or other more elaborate and expensive fastening devices such as screws must be employed. This considerably increases both labor and material costs and unless precautions are taken the construction generally is not as sound as it might be.

The objects of the present invention are to provide a nail which will have adequate holding power in most types of building material, to provide a self locking nail which will have a gripping effect similar to that of a wood screw but which may be driven home with a hammer in the same manner as a conventional nail, to ensure that the nail will not become loose when the Wood in which it is embedded expands or is subjected to vibration, and to provide such a device which is economical to both manufacture and use.

These and still further objects will appear in the following specification and be shown in the accompanying drawing in which:

FIGURE 1 is a side elevation of the nail with part broken away.

FIGURE 2 is an enlarged sectional plan taken on a line 22 of FIG. 1.

FIGURE 3 is a fragmentary detail perspective view showing the toothed rim of the nail head.

The present nail is made with a cylindrical shank having a point 11 and a head 12. On the peripheral surface of the shank, a number of integrally formed lugs 14 are provided, which lugs are substantially in the form of inverted half cones. Each lug has a base or, in this instance, an upper face 15 which is disposed at right angles to the longitudinal axis of the nail. The face 15 has a semi-circular edge 16 which merges with the shank surface at points 17 and 18. The curved side 19 of the lug tapers down to an apex or lower end 20 and this end is disposed to one side or is disaligned with respect to the radial centre of the upper face 15 so that the half cones are distorted to this extent.

The lugs 14 are equidistantly spaced apart, both vertically and horizontally, and this spaced and staggered arrangement of the lugs places their points 17 and tips 20 upon a common line 22 which is helically wound around the cylindrical surface of the shank. Thus the lugs 14 define a single but interrupted thread having an extremely large or coarse pitch as shown in FIGURE 1.

3,233,498 Patented Feb. 3, 1966 "ice The head 12 is a fiat circular member which preferably has a diameter at least three times as great as that of the shank 10. The top surface of the head may be roughened as at 25 and the side edge 26 of this member has a depending rim 27. As shown in FIG. 3 only, the rim 27 is suitably notched during the nail forming process to provide said rim with radially disposed teeth 23.

In use the nail is driven into the board in the same manner as a conventional nail. As the present fastener is hammered home, the lugs 14 cut a rough helical groove in the board material and by so doing impart a slight rotative movement to the nail so that it is advanced somewhat in the manner of a screw fastener.

When the nail has been fully driven home the upper faces 15 are disposed vertically below a portion of the board material which has been relatively undamaged by the entrance of the nail. If the nail is subjected to a force which tends to pull it out of the board, the edges 16 of the lugs bite into the undamaged board material and said material, coming into contact with the faces 15 of said lugs, offers strong resistance to movement of the nail in this direction. The nail would be more readily withdrawn if it could be rotated through the same helical path through which it was driven home. However the teeth 28 tend to resist rotation of the nail and this resistance to rotation augments the self locking action of the lugs to increase the holding power of the fastener. It will be noted that the present nail does not rely solely on cohesion between the shank surface and the wood fibres for its holding power as does the conventional fastener. Thus, if the wood expands or is vibrated as a floor board is vibrated in use, the nail does not become loose so as to Weaken or impair the nailed structure.

What I claim is:

A nail comprising a cylindrical shank having a point at one end and a head at the other end, a plurality of integrally formed lugs on the periphery of the shank, each of the lugs having an upper face, a curved outer face, side edges and a lower end, said upper face being disposed at substantially right angles to the longitudinal axis of the nail and having a semi-circular outer edge, said curved outer edge being reduced in diameter from the upper face to the lower end, said side edges meeting to form a point at the lower end with one of the side edges of each lug being disposed on a comm-on helix line wound around the shank, said lower end being displaced to one side of the center of the upper face, said lugs greater than the diameter of said upper face, said lugs being substantially equidistantly spaced apart vertically and horizontally and extending in a single row whereby to form an interrupted thread on the periphery of the shank.

References Cited by the Examiner UNITED STATES PATENTS 712,245 10/1902 Betts et a1. 21 2,269,708 1/1942 Dickson 85-20 2,558,379 6/1951 Phipard 151-37 2,959,204 11/1960 Rigot ISL-37 FOREIGN PATENTS 1,115,028 12/1955 France.

508,673 7/1939 Great Britain.

EDWARD C. ALLEN, Primary Examiner. 

